U.S. patent application number 11/351010 was filed with the patent office on 2007-08-09 for method for determining windshield condition and an improved vehicle imaging system.
Invention is credited to Stephen H. Fox.
Application Number | 20070182816 11/351010 |
Document ID | / |
Family ID | 38069307 |
Filed Date | 2007-08-09 |
United States Patent
Application |
20070182816 |
Kind Code |
A1 |
Fox; Stephen H. |
August 9, 2007 |
Method for determining windshield condition and an improved vehicle
imaging system
Abstract
An imaging system for use in a vehicle is disclosed wherein the
imaging system images an object spaced apart from the vehicle in a
first configuration and images an object supported by the vehicle
in a second configuration. The imaging system may include a fluid
lens. An imaging system for use in a vehicle is disclosed wherein
the imaging system has a first configuration corresponding to a
first imaging application and a second configuration corresponding
to a second imaging application. The imaging system may include a
fluid lens.
Inventors: |
Fox; Stephen H.; (Kokomo,
IN) |
Correspondence
Address: |
DELPHI TECHNOLOGIES, INC.
M/C 480-410-202
PO BOX 5052
TROY
MI
48007
US
|
Family ID: |
38069307 |
Appl. No.: |
11/351010 |
Filed: |
February 9, 2006 |
Current U.S.
Class: |
348/118 |
Current CPC
Class: |
B60S 1/0862 20130101;
B60S 1/0844 20130101; G02B 3/14 20130101; G02B 26/004 20130101;
G02B 13/0075 20130101; G01N 2021/157 20130101; G01N 21/958
20130101; G01N 21/15 20130101; B60S 1/0837 20130101; G02B 27/0101
20130101; G02B 26/005 20130101; G02B 2027/0118 20130101 |
Class at
Publication: |
348/118 |
International
Class: |
H04N 7/18 20060101
H04N007/18 |
Claims
1. An imaging system for use with a vehicle, the vehicle including
a window through which light is transmitted, the imaging system
comprising: a detector which provides an image of the light
transmitted through the window; imaging optics having a first
configuration wherein an object spaced apart from the vehicle is
imaged onto the detector and a second configuration wherein at
least a portion of the window is imaged onto the detector; and a
controller operably coupled to the imaging optics, the controller
configured to adjust the imaging optics to place the imaging optics
in the first configuration to image the object spaced apart from
the vehicle and further configured to adjust the imaging optics to
place the imaging optics in the second configuration to image the
portion of the window.
2. The imaging system of claim 1, wherein a relative placement of
the imaging optics remains constant as the imaging optics are
adjusted between the first configuration and the second
configuration.
3. The imaging system of claim 1, wherein the imaging optics
includes a variable focus lens.
4. The imaging system of claim 3, wherein a shape of the variable
focus lens is adjusted by the controller, the variable focus lens
having a first shape corresponding to the first configuration of
the imaging optics and a second shape corresponding to the second
configuration of the imaging optics.
5. The imaging system of claim 4, wherein the controller executes
instructions to adjust the shape of the variable focus lens to the
second shape and to analyze an image of the window to determine a
condition of the window.
6. The imaging system of claim 5, wherein the controller further
executes instructions to provide an indication to a driver of the
vehicle if the condition of the window is other than
acceptable.
7. The imaging system of claim 5, wherein the controller further
executes instructions to adjust the shape of the variable focus
lens to the first shape and to execute an imaging application
wherein one or more images of the object spaced apart from the
vehicle are analyzed.
8. The imaging system of claim 7, wherein the controller maintains
the variable focus lens in the first shape until the imaging
application malfunctions whereat the controller adjusts the shape
of the variable focus lens to the second shape to analyze an image
of the window to determine a condition of the window.
9. The imaging system of claim 8, wherein the image of the window
is compared to at least one reference image of the window to
determine the condition of the window.
10. The imaging system of claim 8, wherein the controller further
executes instructions to provide a first indication to a driver of
the vehicle if the condition of the window is other than acceptable
and to provide a second indication to the driver of the vehicle if
the condition of the window is acceptable, the second indication
indicating the imaging application requires maintenance.
11. The imaging system of claim 7, wherein the controller
alternates the imaging optics between the first configuration and
the second configuration, one or more images of the object being
spaced apart from the vehicle being detected by the detector while
the imaging optics are in the first configuration and one or more
images of the window being detected by the detector while the
imaging optics are in the second configuration.
12. The imaging system of claim 1, wherein the imaging optics are
placed in a third configuration by the controller to image a second
portion of the window.
13. The imaging system of claim 1, wherein the variable focus lens
is a fluid lens.
14. The imaging system of claim 13, wherein the shape of the
variable focus lens is adjusted by adjusting a voltage applied to a
fluid of the variable focus lens.
15. An imaging system for use with a vehicle, the vehicle including
a window through which light is transmitted, the imaging system
comprising: a detector which provides an image of the light
transmitted through the window; imaging optics having a first
configuration wherein a first object spaced apart from the vehicle
is imaged onto the detector and a second configuration wherein a
second object supported by the vehicle is imaged onto the detector;
and a controller operably coupled to the imaging optics, the
controller configured to adjust the imaging optics to place the
imaging optics in the first configuration to image the first object
and further configured to adjust the imaging optics to place the
imaging optics in the second configuration to image the second
object.
16. The imaging system of claim 15, wherein a relative placement of
the imaging optics remains constant as the imaging optics are
adjusted between the first configuration and the second
configuration.
17. The imaging system of claim 16, wherein the second object is an
object placed on a dashboard of the vehicle.
18. The imaging system of claim 17, wherein the variable focus lens
is a fluid lens.
19. An imaging system for use with a vehicle, the vehicle including
a window through which light is transmitted, the imaging system
comprising: a detector which provides an image of the light
transmitted through the window; imaging optics including a variable
focus lens positioned to focus light on the detector, the imaging
optics having a first configuration corresponding to a first
imaging application analyzing one or more objects spaced apart from
the vehicle and having a second configuration corresponding to a
second imaging application analyzing one or more objects spaced
apart from the vehicle; and a controller operably coupled to the
variable focus lens, the controller configured to adjust a shape
the variable focus lens, wherein the first imaging configuration
corresponds to a first shape of the variable focus lens and the
second imaging configuration corresponds to a second shape of the
variable focus lens.
20. The imaging system of claim 19 wherein the controller adjusts
the shape of the variable focus lens to a third shape wherein the
imaging optics are configured to image the window of the
vehicle.
21. The imaging system of claim 19, wherein the controller adjusts
the shape of the variable focus lens to a third shape wherein the
imaging optics are configured to image a dashboard of the
vehicle.
22. The imaging system of claim 19, wherein the variable focus lens
is a fluid lens.
23. A method for detecting problems with an imaging system for a
vehicle, the imaging system looking at a scene through a window of
the vehicle, the method comprising the steps of: identifying a
degraded optical quality of the window with an optical system
having a variable focus lens; and alerting a driver of the vehicle
of the degraded optical quality of the window.
24. The method of claim 23, wherein the step of identifying the
degraded optical quality of the window includes the steps of:
adjusting a focal length of the variable focus lens of the optical
system to image at least a portion of the window; and detecting an
unacceptable condition of the window based on an analysis of an
image of the window.
25. The method of claim 23, wherein the step of alerting the driver
of the vehicle of the degraded optical quality of the window
includes the step of providing an indication with a visual
indicator to the driver of the vehicle of the degraded optical
quality of the window.
26. A method for detecting problems with an imaging system for a
vehicle, the imaging system looking at a scene through a window of
the vehicle, the method comprising the steps of: imaging the scene
with the imaging system; adjusting the imaging system to image at
least a portion of the window; imaging the at least a portion of
the window; and analyzing the imaged portion of the window to
detect if a degraded optical quality of the window is present.
27. The method of claim 26, wherein the imaging system includes at
least one variable focus lens.
28. The method of claim 27, wherein the step of adjusting the
imaging system to image at least a portion of the window to detect
if a degraded optical quality of the window is present includes the
step of altering a shape of the variable focus lens.
29. The method of claim 26, further comprising the step of alerting
a driver of the vehicle of the degraded optical quality of the
window if the degraded optical quality of the window is present.
Description
TECHNICAL BACKGROUND
[0001] The present invention relates to an imaging system for use
in a vehicle, in particular an imaging system including optics that
permits the imaging system to image objects within the vehicle, a
window of the vehicle, and objects spaced apart from the
vehicle.
BACKGROUND OF THE INVENTION
[0002] Imaging systems are used with vehicles. Some imaging systems
are located behind a window of the vehicle and image objects that
are spaced apart from the vehicle. Exemplary imaging systems
include lane tracking systems, lane departure warning systems,
adaptive cruise control systems, night vision systems, frontal
imaging systems, side imaging systems, rear imaging systems,
collision warning systems, and pedestrian/cross traffic
identification systems.
[0003] The condition or optical quality of the window through which
the imaging system looks may impede the operation of the imaging
system. For example, in the case of a forward looking vision system
the optical quality of the windshield of the vehicle may be
degraded by fog, frost, dirt, or other objects which cloud the
scene or objects being imaged and lower the signal contrast of the
image. Further, scratches, rock chips, and bird droppings cause
obstructions that may cause false positive warnings, or inhibit
correct identification of genuine targets. These conditions may
disrupt the operation of the respective vision system and may lead
to an indication that the vision system is not functioning properly
when in reality only the optical quality of the window needs to be
improved.
[0004] It is known to detect the presence of precipitation on a
windshield of a vehicle by total internal reflection. A beam of
light is reflected from the windshield at a particular angle. The
presence of water on the windshield defeats this reflection causing
a change in the intensity of light received at the detector.
Further, it is known to include an LED in a camera housing whose
emitted light is reflected off of the windshield. The pattern of
the reflected light is evaluated to determine the windshield
condition.
[0005] In addition to the optical quality of the windshield,
forward-looking cameras are subject to reflections from the inside
of the windshield. Objects placed on the dashboard appear in the
field of view of the vision system through the partially reflecting
property of the windshield. One solution to this problem has been
placing a non-reflecting light shield underneath the optics of the
imaging system to prevent such reflections from entering the
imaging system. Such a shield is large and must be redesigned for
each model automobile into which the imaging system is placed.
Another solution has been the inclusion of a polarizing element to
eliminate the typically polarized reflections from the windshield
from entering the imaging system. However, such polarizer elements
cut the detector sensitivity by half as they eliminate half of the
incoming light and do not function well over the full range of
incidence angles.
SUMMARY OF THE INVENTION
[0006] The present invention provides improved imaging systems for
vehicles that monitor objects spaced apart from the vehicle,
objects supported by the vehicle including a window of the vehicle,
or both objects spaced apart from the vehicle and objects supported
the vehicle.
[0007] In an exemplary embodiment of the present invention an
imaging system for use with a vehicle is provided. The vehicle
including a window through which light is transmitted. The imaging
system comprising a detector which provides an image of the light
transmitted through the window; imaging optics and a controller.
The imaging optics having a first configuration wherein an object
spaced apart from the vehicle is imaged onto the detector and a
second configuration wherein at least a portion of the window is
imaged onto the detector. The controller operably coupled to the
imaging optics. The controller configured to adjust the imaging
optics to place the imaging optics in the first configuration to
image the object spaced apart from the vehicle and further
configured to adjust the imaging optics to place the imaging optics
in the second configuration to image the portion of the window.
[0008] In another exemplary embodiment of the present invention an
imaging system for use with a vehicle is provided. The vehicle
including a window through which light is transmitted. The imaging
system comprising a detector which provides an image of the light
transmitted through the window; imaging optics, and a controller.
The imaging optics having a first configuration wherein a first
object spaced apart from the vehicle is imaged onto the detector
and a second configuration wherein a second object supported by the
vehicle is imaged onto the detector. The controller operably
coupled to the imaging optics. The controller configured to adjust
the imaging optics to place the imaging optics in the first
configuration to image the first object and further configured to
adjust the imaging optics to place the imaging optics in the second
configuration to image the second object.
[0009] In yet a further exemplary embodiment of the present
invention an imaging system for use with a vehicle is provided. The
vehicle including a window through which light is transmitted. The
imaging system comprising a detector which provides an image of the
light transmitted through the window; imaging optics; and a
controller. The imaging optics including a variable focus lens
positioned to focus light on the detector. The imaging optics
having a first configuration corresponding to a first imaging
application analyzing one or more objects spaced apart from the
vehicle and having a second configuration corresponding to a second
imaging application analyzing one or more objects spaced apart from
the vehicle. The controller operably coupled to the variable focus
lens. The controller configured to adjust a shape the variable
focus lens, wherein the first imaging configuration corresponds to
a first shape of the variable focus lens and the second imaging
configuration corresponds to a second shape of the variable focus
lens.
[0010] In still another exemplary embodiment of the present
invention, a method for detecting problems with an imaging system
for a vehicle is provided. The imaging system looking at a scene
through a window of the vehicle. The method comprising the steps of
identifying a degraded optical quality of the window with an
optical system having a variable focus lens; and alerting a driver
of the vehicle of the degraded optical quality of the window. In
one example, the step of identifying the degraded optical quality
of the window includes the steps of adjusting a focal length of a
variable focus lens of an imaging system to image at least a
portion of the window; and detecting an unacceptable condition of
the window based on an analysis of an image of the window. In
another example, the step of alerting the driver of the vehicle of
the degraded optical quality of the window includes the step of
providing an indication to a driver of the vehicle of the degraded
optical quality of the window.
[0011] In a further exemplary embodiment of the present invention,
a method for detecting problems with an imaging system for a
vehicle is provided. The imaging system looking at a scene through
a window of the vehicle. The method comprising the steps of:
imaging the scene with the imaging system; adjusting the imaging
system to image at least a portion of the window; imaging the at
least a portion of the window; and analyzing the imaged portion of
the window to detect if a degraded optical quality of the window is
present.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The above-mentioned and other features and objects of this
invention, and the manner of attaining them, will become more
apparent and the invention itself will be better understood by
reference to the following description of embodiments of the
invention taken in conjunction with the accompanying drawings,
wherein:
[0013] FIG. 1 is a representative diagram of a vehicle including a
window and an imaging system which images objects or a scene of
interest that is spaced apart from the vehicle;
[0014] FIG. 2 is a flowchart of an exemplary method to be executed
by the imaging system of FIG. 1;
[0015] FIG. 3 is a representative view of another exemplary imaging
system;
[0016] FIG. 4 is a flowchart of an exemplary method to be executed
by the imaging system of FIG. 3;
[0017] FIG. 5 is a flowchart of another exemplary method to be
executed by the imaging system of FIG. 3;
[0018] FIG. 6 is a representative view of a further exemplary
imaging system; and
[0019] FIG. 7 is a flowchart of an exemplary method to be executed
by the imaging system of FIG. 6.
[0020] Corresponding reference characters indicate corresponding
parts throughout the several views. Although the drawings represent
embodiments of the present invention, the drawings are not
necessarily to scale and certain features may be exaggerated in
order to better illustrate and explain the present invention. The
exemplifications set out herein illustrate embodiments of the
invention in several forms and such exemplification is not to be
construed as limiting the scope of the invention in any manner.
DESCRIPTION OF INVENTION
[0021] The embodiments discussed below are not intended to be
exhaustive or limit the invention to the precise forms disclosed in
the following detailed description. Rather, the embodiments are
chosen and described so that others skilled in the art may utilize
their teachings.
[0022] Referring to FIG. 1, a vehicle 100 is shown. Exemplary
vehicles include automobiles, trucks, airplanes, watercraft, and
other exemplary motorized vehicles. Vehicle 100 includes a window
102. Exemplary windows include a front windshield, a rear
windshield, one or more side windows, and any other suitable
optically transparent regions that permit optical radiation 104,
preferably visible light and/or non-visible light, such as infrared
light, to enter an envelope of vehicle 100. The light 104 entering
vehicle 100 is incident on imaging optics 108 of an imaging system
110. Imaging optics 108 form an image of a scene including one or
more objects 112 on a detector 114 of imaging system 110. In one
embodiment, detector 114 provides a digital image of the scene.
Object 112 is shown spaced apart from vehicle 100. Exemplary
objects include pedestrians, bicyclists, animals, trees, other
vehicles, road signs, and any other object which may be positioned
in the general vicinity of vehicle 100. In one embodiment, object
112 is spaced apart from imaging optics 108 from about 2 meters to
about 150 meters. In another embodiment, object 112 is spaced apart
from imaging optics 108 by at least about 2 meters. In another
embodiment, imaging optics 108 are arranged to image objects within
vehicle 100 such as passengers, eyes of driver, car seats, and
other objects.
[0023] Imaging optics 108 may include multiple optical elements
such as lens, mirrors, and prisms whose optical characteristics and
spacing is selected based on the desired imaging application. In
one embodiment, the relative location of the various optical
elements is set. In one embodiment, imaging optics 108 includes a
variable focus lens 120 whose focal length may be adjusted. In
another embodiment, imaging optics 108 includes a variable focus
lens 120 and one or more conventional optical elements each having
a fixed focus, such as glass or plastic optics. In another
embodiment, imaging optics 108 may include at least two variable
focus lenses 120 and may include additional conventional
optics.
[0024] Imaging system 110 further includes a controller 116 which
is configured to analyze the images formed on detector 114 and to
provide one or more indications to an occupant of vehicle 100, such
as with an indicator 118. Exemplary indicators include, lights on
an instrument panel, chimes, haptic, and other suitable indicators.
Further, controller 116 is configured to provide input signals to a
vehicle control system 121, such as a processor, an actuator, a
motor, circuitry, and another suitable controller, which in turn
controls the operation of the one or more vehicle systems 122 of
vehicle 100, such as brakes, suspension, steering, air bags,
restraints, and other components of vehicle 100. In one example,
controller 116 in response to the detection of a potential
collision provides an input to an occupant restraint control system
which increases the tension of a restraint or seat belt.
[0025] Exemplary applications of imaging system 110 include lane
tracking systems, lane departure warning systems, adaptive cruise
control systems, night vision systems, frontal imaging systems,
side imaging systems, rear imaging systems, collision warning
systems, pedestrian/cross traffic identification systems, and other
suitable systems which based on images monitor one or more objects
spaced apart from vehicle 100. Exemplary imaging systems are
disclosed in U.S. Pat. No. 5,933,277; U.S. Pat. No. 5,935,161; and
U.S. patent application Ser. No. 10/919,163, filed Aug. 16, 2004,
Attorney Docket No. DP-311476, titled "Refractive Block and Imaging
Systems," the disclosures of which are expressly incorporated by
reference herein. Exemplary imaging systems also include systems
which monitor objects within vehicle 100, such as the occupant
position systems and driver gaze systems described in U.S. patent
application Ser. No. 10/975,264, filed Oct. 28, 2004, Attorney
Docket No. DP-310554, titled "Actively-Illuminating Optical Sensing
System for an Automobile," the disclosure of which is expressly
incorporated by reference herein.
[0026] In the illustrated embodiment shown in FIG. 1, controller
116 has access to a computer readable medium, memory 124, which
includes software that is executed by controller 116. In the
illustrated embodiment, memory 124 includes software related to a
first imaging application 126A and a second imaging application
126B. The optical requirements for imaging optics 108 typically
vary from application to application. For instance, an exemplary
lane departure warning application requires imaging optics 108 to
have a field of view of about 45 degrees while an exemplary night
vision application requires imaging optics 108 to have a field of
view of about 24 degrees. Further, the exemplary night vision
application requires higher resolution performance on axis than the
exemplary lane departure warning application. Thus, integrating the
optical requirements of both the exemplary lane departure
application and the exemplary night vision application into the
same fixed imaging optics compromises the performance of one
application or the other.
[0027] The incorporation of multiple imaging applications 126A and
126B into imaging system 110 is possible without sacrificing the
performance of either application because imaging optics 108 may be
reconfigured to accommodate the optical requirements of each
application. In the illustrated embodiment, imaging optics 108
includes variable lens 120 which has an adjustable focal length. By
adjusting the focal length of variable lens 120 various parameters
of imaging optics 108 may be adjusted such as the focal length of
imaging optics 108, the depth of focus of imaging optics 108, the
object range of imaging optics 108, the field of view of imaging
optics 108, the resolution of imaging optics 108, and the
magnification of imaging optics 108. In one embodiment, imaging
optics 108 includes two or more variable lens 120 to achieve the
adjustment of one or more of the above-mentioned optical
parameters.
[0028] In one embodiment, a focal length of variable focus lens 120
is changed by changing a shape of variable focus lens 120. As such,
a parameter of imaging optics 108 may be altered without adjusting
the relative location of one or more components of imaging optics
108. In one embodiment, variable focus lens 120 is a liquid lens.
An exemplary liquid lens includes two immiscible fluids contained
within a cylindrical housing. The shape of the boundary between the
two fluids changes in response to the application of a voltage to
the conductive fluid. In the illustrated embodiment, the shape of
variable focus lens 120 is adjusted by altering a voltage across
variable focus lens 120, the voltage being applied through an
electrode of a power source 130. Exemplary fluid lens include the
FluidFocus fluid lens available from Philips Research located at
Koninklijke Philips Electronics N.V. Groenewoudseweg 1 5621 BA,
Eindhoven the Netherlands and a fluid lens available from Varioptic
located at Batiment Tony Garnier--8 B Rue Hermann Frenkel 69007
Lyon France. Additional details about suitable fluid lens are
provided in U.S. Pat. No. 6,369,954, Ser. No. 09/529,193, issued
Apr. 9, 2002 to Berge et al; U.S. Published Application No.
2005/0002113A1, Ser. No. 10/812,307, filed Mar. 30, 2004;
International Application No. WO 00/58763; and International
Application No. WO 99/18456, the disclosures of which are expressly
incorporated by reference herein.
[0029] The voltage applied to variable focus lens 120 may be
adjusted by controller 116. As such, controller 116 may configure
imaging optics 108 for a first application, such as a lane
departure warning application, and then reconfigure imaging optics
108 for a second application, such as a night vision application by
adjusting the voltage applied to variable focus lens 120. The
configuration of imaging optics 108 may be altered by controller
116 on a demand basis such as the activation of a second imaging
application, based on other conditions, such as failure of a given
imaging application and driver intervention. Variable lens 120
permits the ability to change a parameter of imaging optics 108
without having to move the location of a component of imaging
optics 108.
[0030] In an exemplary embodiment, controller 116 is programmed to
execute method 200 illustrated in FIG. 2. Controller 116 adjusts
variable lens 120 to image a scene or objects of interest for first
application 126A on detector 114, as represented by step 202. One
or more images of the scene or objects of interest 112 for first
application 126A are captured by controller 116, as represented by
block 204. Controller 116 analyzes the captured one or more images
for first application 126A, as represented by block 206. Further,
after the completion of block 204, controller 116 adjusts variable
lens 120 to image a scene or objects of interest 112 for a second
application 126B on detector 114, as represented by step 208. One
or more images of the scene or objects of interest 112 for second
application 126B are captured by controller 116, as represented by
block 210. Controller 116 analyzes the captured one or more images
for second application 126B, as represented by block 212.
[0031] In one embodiment, controller 116 adjusts variable focus
lens 120 and hence imaging optics 108 between each image frame
captured with detector 114. Thus, although a single set of imaging
optics 108 is used, each imaging application may have imaging
optics 108 configured for that imaging application.
[0032] In one embodiment, imaging system 110 may perform a
diagnosis of the condition or optical quality of window 102. Poor
optical quality of window 102 may result in one or more of first
application 126A and second application 126B not functioning
properly and/or may degrade the usefulness of the images obtained
by imaging system 110. For example, in the case of a forward
looking vision system the optical quality of the windshield of
vehicle 100 may be degraded by fog, frost, dirt, etc., which cloud
the scene and lower the signal contrast. Further, scratches, rock
chips, and bird droppings cause obstructions that may cause false
positive warnings, or inhibit correct identification of genuine
targets. These conditions may disrupt the operation of the
respective imaging application 126 and may lead to an indication
that imaging system 110 is not functioning properly when in reality
only the optical quality of window 102 needs to be improved.
[0033] To diagnosis the optical quality of window 102, imaging
optics 108 are adjusted to image at least a portion of window 102
on detector 114. Typically, when configured for use with one of
first application 126A and second application 126B imaging optics
108 form an image of object(s) or scene 112 on detector 114.
Objects or scene 112 is typically from about 2,000 millimeters (mm)
to about 150,000 mm spaced apart from imaging optics 108 of vehicle
100. Assuming that imaging optics may be approximated as a thin
lens system, then an image of object(s) or scene 112 is formed
generally at the focus of imaging optics 108 in accordance with
equation 1, 1 z 1 + 1 z 2 = 1 f ( 1 ) ##EQU1## wherein z.sub.1 is
the distance from object 112 to imaging optics 108, z.sub.2 is the
distance from imaging optics 108 to an image of object 112, and f
is the focal length of imaging optics 108. Assuming that the focal
length of imaging optics 108 is generally about 6 mm, then equation
1 may be reduced to equation 2. 1 z 2 = 1 f ( 2 ) ##EQU2## However,
window 102 is typically about 5 mm to about 20 mm from imaging
optics 108. Regarding the imaging of window 102, the term 1/z1 of
equation 1 is not negligible as in the case of object 112 which is
about 200 times to about 30,000 times further from imaging optics
108 than window 102. As such, assuming that detector 114 is about 8
mm from imaging optics 108 and the window 102 is about 20 mm from
imaging optics the focal length of imaging optics 108 should be
about 5.7 mm. Based on the typical focal length of 6 mm given
above, the focal length of imaging optics 108 is reduced by about 5
percent to image window 102.
[0034] By using variable lens 120, the focal length of imaging
optics 108 may be adjusted between imaging object(s) or scene 112
and window 102, such as windshield 140 illustrated in FIG. 3 or
another plane of interest. In one embodiment, controller 116 is
programmed to compare an image of windshield 140 to one or more
reference images 141 of windshield 140 stored in memory 124. Based
on that comparison, the condition or optical quality of windshield
140 may be assessed. The data in the image of windshield 140
corresponding to objects 112 will be out of focus and would only
affect the relative intensity of the image of windshield 140. This
relative intensity may be accounted for by low pass filtering (edge
detection) in the image.
[0035] In another embodiment, controller 116 is configured to
analyze an image of windshield 140 for various image properties,
such as the presence of significant higher frequency indicia
indicating a non-smooth windshield, artifacts, or varying contrast.
Independent of the manner of diagnosing windshield 140 the
instructions executed by controller 116 are provided by a window
application 142 stored in memory 114. Additional techniques that
may be used in the analysis of windshield 140 are generally similar
to the techniques use in other imaging applications and may include
contrast discrimination, motion, template matching, and other
suitable image analysis techniques.
[0036] Referring to FIG. 4, an exemplary method 300 of window
application 142 is illustrated. Controller 116 executes
instructions related to first application 126A, as represented by
block 201 which includes blocks 202, 204, and 206 in FIG. 2.
Controller 116 determines if first application 126A is operating
correctly, as represented by block 302. Examples of incorrect
operation include insufficient contrast for a collision warning
system, obscured lane markers for a lane detection system, no image
present (low light level) for all such systems, and other types of
incorrect operation.
[0037] If first application 126A is not operating correctly, the
condition of windshield 140 is diagnosed to determine if the
optical quality of windshield 140 is a potential reason for the
failure of the first application 126A. Controller 116 adjusts
variable lens 120 so that imaging optics 108 image windshield 140
on detector 114, as represented by block 306. Controller 116
captures one or more images of windshield 140, as represented by
block 308. The captured one or more images of windshield 140 are
analyzed to determine the condition or optical quality of
windshield 140, as represented by block 310. Several techniques of
analyzing the one or more images of windshield 140 are discussed
above. As illustrated in FIG. 4, in one embodiment, a stored
reference image of windshield 140 is retrieved, as represented by
block 312, for comparison to the captured one or more images of
windshield 140.
[0038] In one embodiment, assuming the region of windshield 140
whose condition is relevant to the operation of imaging system 110
is region A, the condition of windshield 140 may need to be
determined through multiple iterations because of the slope of
windshield 140 relative to the axis of imaging optics 108. For
example, variable lens 120 may be adjusted to image sub-region B of
windshield 140 and to analyze the condition of sub-region B and
then adjusted to image sub-region C and to analyze the condition of
sub-region C. In one embodiment, windshield 140 may be imaged and
analyzed in strips.
[0039] Controller 116 determines if the condition of the windshield
140 is acceptable, as represented by block 314. If the condition of
windshield 140 is not acceptable, then controller 116 provides an
indication to the driver of vehicle 100 through indicator 118 to
inspect windshield 140, as represented by block 316. If the
condition of windshield 140 is acceptable, then controller 116
provides an indication to the driver of vehicle 100 through
indicator 118 that the respective application 126A, 126B requires
maintenance, as represented by block 318.
[0040] Method 300 of FIG. 4 represents an exemplary method wherein
the condition of windshield 140 is checked in response to a failure
of a respective imaging application 126A, 126B. Referring to FIG.
5, a method 350 is illustrated which represents an exemplary method
wherein the condition of windshield 140 in intermittently checked
regardless of the presence or absence of a failure of a respective
imaging application 126A, 126B. In one embodiment, the condition of
windshield 140 may be checked periodically.
[0041] Referring to FIG. 5, controller 116 executes instructions
related to first application 126A, as represented by block 201
which includes blocks 202, 204, and 206 in FIG. 2. Controller 116
executes instructions to diagnosis the condition or optical quality
of windshield 140, as represented by block 301 which includes
blocks 306, 308, 310 and optionally block 312 of FIG. 4. Controller
116 determines if the condition of the windshield 140 is
acceptable, as represented by block 314. If the condition of
windshield 140 is not acceptable, then controller 116 provides an
indication to the driver of vehicle 100 through indicator 118 to
inspect windshield 140, as represented by block 316. If the
condition of windshield 140 is acceptable, then controller 116
executes instructions related to second application 126B, as
represented by block 207 which includes blocks 208, 210, and 212 in
FIG. 2. In the illustrated embodiment, controller 116 executes
instructions related to second application 126B regardless of
whether the condition of windshield 140 is acceptable or not
acceptable.
[0042] Subsequent to executing instructions related to second
application 126B, as represented by block 207, controller 116 again
executes instructions to diagnose the condition of windshield 140,
as represented by block 301 and as discussed above. In one
embodiment, the condition of windshield 140 is only checked
subsequent to one of first application 126A or second application
126B. In another embodiment, the condition of windshield 140 is
checked independent of the operation of another application. In a
further embodiment, the condition of windshield 140 alternates
execution by controller 116 with a single other application, such
as first application 126A. It should be understood that although
the diagnosis of windshield 140 is discussed as being separate from
first application 126A or second application 126B, one or more of
these functions may be provided in a single software package. Each
is discussed separately to highlight the functionality of each and
not as a limitation.
[0043] Variable lens 120 may be used for other applications. For
instance, variable lens 120 may be used to adjust the focal length
of imaging optics 108 to image an object 144 (see FIG. 6) within
vehicle 100, such as papers on a dashboard 146 (see FIG. 6) of
vehicle 100. Other objects include passengers, portions of a
passenger such as eyes, car seats, or other objects. Referring to
FIG. 6, controller 116 is programmed with a reflection application
148 to image object 144 and to alter an image of scene or objects
112 based on the image of object 144. As such, the effect of
reflections from object 144 entering imaging optics 108 may be
accounted for without a sacrifice of the light entering imaging
optics 108 or the need of an additional shield.
[0044] Referring to FIG. 7, controller 116 executes first
application 126A, as represented by block 201 and determines
whether first application 126A is operating correctly, as
represented by block 302. If first application 126A is operating
correctly, controller 116 executes a second application 126B, if
present, as represented by block 207, or simply continues the
execution of first application 126A. If second application 126B is
executed, controller 116 determines whether second application 126B
is operating correctly, as represented by block 304.
[0045] If either of first application 126A or second application
128B is not operating correctly, controller 116 diagnoses
windshield 140, as represented by block 301. Controller 116
determines if the condition of windshield 140 is acceptable, as
represented by block 314. If the condition of windshield 140 is not
acceptable, then controller 116 provides an indication to the
driver of vehicle 100 to inspect windshield 140, as represented by
block 316. In one embodiment, controller 116 does not diagnosis the
condition of windshield 140.
[0046] Regardless of whether controller 116 diagnoses the condition
of windshield 140, controller 116 adjusts variable lens 120 to
image dashboard 146, as represented by block 402. Controller 116
captures one or more images of dashboard 146, as represented by
block 404. The ability to periodically focus on dashboard 146 may
provide, in one embodiment, the ability to distinguish between
object 144 on dashboard 146 inside vehicle 100 and objects 112
outside vehicle 100. Controller 116 adjusts the images of objects
or scene 112 captured by controller 116 for the failed first
application 126A or second application 126B based on the one or
more images captured by controller 116, as represented block
406.
[0047] In one embodiment, controller 116 adjusts the images of
objects or scene 112 by automatic control of gain and dynamic range
compression.
[0048] Controller 116 determines if the adjusted images are able to
be analyzed by the respective first application 126A or the second
application 126B, as represented by block 408. If the adjusted
image is not able to be analyzed, controller 116 provides an
indication to the driver that the respective application 126A, 126B
requires maintenance, as represented by block 318. If the adjusted
image is able to be analyzed, controller 116 returns to executing
the next of the first application 126A and second application
126B.
[0049] While this invention has been described as having an
exemplary design, the present invention may be further modified
within the spirit and scope of this disclosure. This application is
therefore intended to cover any variations, uses, or adaptations of
the invention using its general principles. Further, this
application is intended to cover such departures from the present
disclosure as come within known or customary practice in the art to
which this invention pertains.
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